Addison's Disease Flashcards
What is another name for Addison’s Disease?
Hypoadrenocorticism
What causes Addison’s disease?
Usually it is primary adrenal failure [decreased to no production of glucocorticoids-cortisol and mineralocorticoids- aldosterone] via immune mediated destruction of the cortex of the adrenal glands. It can also be caused iatrogenically when treating Cushing’s with Mitotane or Trilostane or from chronic use of glucocorticoids, you can get ACTH suppression from the pituitary. You can also get secondary adrenal failure from the failure of the pituitary gland to produce ACTH and stimulate the adrenal glands usually after some sort of CNS trauma. There are other not so common reasons for Addison’s Disease like hemorrhage, infarct, infection or a tumor.
How much of the adrenal gland needs to be destroyed before you get clinical Addisonian signs?
> 85%
What breeds are most commonly effected by Addison’s?
Standard poodles, Portugese Water Dogs, Nova Scotia Duck Tolling Retriever, Rottweiler, WHWT, mixed breeds have the highest prevalence
What are the clinical signs of Addison’s?
This disease is often called “The Great Imitator” so it can really look like anything! Always keep it on your radar. Signs: lethargy, QAR or even obtunded/recumbent, thin, hypothermic, bradycardic, severe dehydration, episodic collapse, vomiting (they are near a crisis when this occurs)/diarrhea (HGE), poor appetite/weight loss, abdominal pain.
What are the 2 types of Addison’s disease?
Primary: Immune mediate destruction of the adrenal cortices.
Secondary: Destructive lesions in the hypothalamus or pituitary leading to less corticotropin releasing hormone or ACTH.
What happens on clin path that we can appreciate when there is a lack of aldosterone being produced?
Excess Na+ secreted and an increase in K+ retention. Hyponatremia can lead to hypovolemia, hypotension and pre-renal azotemia from dehydration. Can eventually lead to an Addisonian crisis. Serum Na:K ratio of <27 is suggestive of Addison’s.
What will we see on a CBC and Chemistry with an Addisonian patient?
Mild-moderate non-regenerative anemia (however you may not appreciate this due to dehydration), lack of a stress leukogram, eosinophilia, increased Ca2+ levels, USG: 1.008-1.030, moderate pre-renal azotemia in 90% of animals due to dehydration (the increases in BUN may be from dehydration or from gastric hemorrhage), severe hyperkalemia, hypoglycemic (from decreased amounts of circulating cortisol, supplement with dextrose).
How would you confirm your suspicions of Addison’s Disease?
Perform an ACTH Stimulation Test
How do you perform an ACTH stim test?
- Draw blood at time 0
- Inject synthetic ACTH/Corticotropin
- Perform a 2nd blood draw in 1 hr for dogs and 30 min for cats.
- Read results (Baseline cortisol should be <1.2 micrograms/dL, and in 1 hr should be >1.8 micrograms/dL but if it isn’t this is diagnostic for Addison’s.)
What happens when there is a lack of cortisol?
Lack of fat distribution and thus a thin patient, lack of gluconeogensis and insulin antagonism (thus we see hypoglycemia and perhaps weakness or a seizure), cortisol is normally anti-inflammatory and immunosuppressive so we may see more inflammation in the body.
How would you treat hyperkalemia in patient?
Saine diuresis, calcium gluconate, regular insulin with concurrent dextrose infusion.
What other tests would you want to do for monitoring in a patient with Addison’s?
EKGs (especially with K+ levels super high), monitor blood pressure (frequently the systolic is in the toilet).
What are the complications of hypoadrencorticism?
- Acute renal failure
- Gastrointestinal hemorrhage
- Pancreatitis
- Pulmonary thromboembolism
- DIC
How will you provide supportive care to animal with Addison’s disease?
Fluids: Dehydration + Ongoing Losses + Maintenance, ex:) 20 kg dog with 10% dehydration= 2 L, maintenance at 60 mL/kg/day = 1.2 L, and an estimated ongoing loss of 0.8 L in total = 4 L or 4000 mL. Use 0.9% NaCl (considered a replacement fluid, and non-buffered 154 mmol/L of Na+). Typically you will replace the first half of the dehydration amount over the first 4-6 hours and the second half over 18-20 hours. So you’d take 1 L or 1000 mL and divide by 4 which would give you 250 mL/hr + (maintenance 1200/24=50 mL/hr) + (ongoing losses 800 mL/24= 34 mL/hr) = 334 mL/hr for the first 4 hours and then you’d take the remaining amount of your dehydration amount and divide by 20. (1000 mL/20=50 mL/hr) and + maintenance 50 mL/hr + ongoing losses 34 mL/hr. So for the remaining 20 hours you’d have 134 mL/hr. . Remember if you give calcium gluconate you will give at 1 mL/kg of 10% solution over 10 minutes but monitor the ECG. Or you can give insulin 0.25 IU/kg of neutral insulin + 1 mL/kg dextrose 50% as a 1:4 dilution over 30 minutes.
